1. Field of the Invention
The present invention relates to a communication control system, a communication control method, a routing controller and a router suitably used for the same.
2. Description of the Related Art
In conventional IP networks, a router exchanges routing information with adjacent routers using a routing protocol such as an OSPF (Open Shortest Path First) and a RIP (Routing Information Protocol), and performs a routing processing of received data based on a destination IP address referring to a routing table created by the routing information.
In the conventional IP networks, an “MPLS (Multi Protocol Label Switching)” technique is known as a traffic engineering technique which can realize a routing path backup for rerouting traffic in the event of a link failure or a node failure, and a traffic load distribution.
The MPLS technique is configured to insert a header which is called a “label” into a lower layer than a layer 3, and to perform a routing path management using the label as a virtual routing path. The MPLS technique is called a “layer 2.5 technique”.
The MPLS technique can realize a traffic engineering including a QoS control, by associating the label with a specific routing path or a QoS class.
However, the conventional router decides the routing path based on the destination IP address, in accordance with the routing table created in the router. Therefore there is a problem in that it is necessary to restructure the routing table using the routing protocol when a hand-over of a mobile station, a congestion or a failure occurs in the IP network, so that communication in the IP network stops for a certain period.
There is a problem in that the conventional router can not change a routing path of a specific flow dynamically during communication.
There is a problem in that the conventional router can not dynamically route IP packets to a special device such as an accounting device, a monitor device and a media converter device.
The MPLS technique can resolve the above problem partly using the label concept. However, there is a problem in that all routers in the IP networks have to support the MPLS technique which is a special protocol, in the above case.
There is a problem in that the MPLS technique is not suitable for the routing control (the flow control) in small units such as IP packets.